Unfortunately, there is little research on the health effects of tire particulate matter. One of the few comprehensive studies completed over ten years ago, in 2012. “It wasn’t decided at the time that it was a priority,” says Gary Guthrie, Michelin’s senior vice president. “A priority topic was to better understand the fate of particles in water and how they are degraded.”
“Research sponsored by the Tire Industry Project (TIP) of the World Business Council for Sustainable Development (WBSCD) has shown that tire and road wear particles (TRWP) do not pose a risk to human health,” says Wanka. “Inhalation studies suggest that TRWP is unlikely to pose a risk to humans through airborne exposure.”
“Tire pollution and NOx emissions are different,” says Erlendson. “NOx is a gaseous by-product of fuel combustion, while tire particulates are a particulate pollutant, similar to dust from wood burners. However, unlike NOx and CO2 from tailpipes, there are currently no global regulations in place that specifically limit tire pollution.
Are biodegradable tires the solution?
Biodegradable tires seem to be a potential solution to the problem of tire pollution. However, there are some paradoxes associated with this idea. “Tires are important for safety,” says Wanka. “They are the only contact between the vehicle and the road. That is why it is so important that the tire does not degrade by the end of the use phase. Many tires can last five years or more.
“While the tire industry is increasingly exploring bio-based materials such as natural rubber, the tires themselves and the pollutants they generate are not yet biodegradable,” says Erlendson. “A tire that biodegrades on a vehicle would not be good in terms of durability. However, it would be beneficial if tire particles emitted while driving could be biodegraded in the environment, preventing them from accumulating in the air, on land and in the oceans.”
“Right now, our focus is on the front end, not the back end,” Guthrie says. This means using more recycled materials in production, aiming for a degree of circularity. “We would prefer to be able to take a tire back at the end of its life and make a modern one, because that is even better for the planet than being able to just put it on flower beds. This way, we won’t have to take raw materials from Earth to produce tires at all.”